Loxorhynchus grandis: Difference between revisions
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The sheep crab has a [[carapace]], four sets of walking legs, and a set of claws, or [[Chela (organ)|chelipeds]]. Males are larger than females. The carapace of a male can be up to {{Convert|17|cm|in|abbr=}} across, while females can grow to {{Convert|11|cm|in|abbr=}}<ref name=":1">{{Cite web|url=https://caseagrant.ucsd.edu/seafood-profiles/sheep-crab|title=Sheep Crab {{!}} California Sea Grant|website=caseagrant.ucsd.edu|access-date=2019-12-28}}</ref>. The carapace is tear-shaped with a wide, rounded posterior which tapers to a point at its snout, or [[Rostrum (anatomy)|rostrum]]. There are two down-curved horns on the rostrum<ref name=":2" />. |
The sheep crab has a [[carapace]], four sets of walking legs, and a set of claws, or [[Chela (organ)|chelipeds]]. Males are larger than females. The carapace of a male can be up to {{Convert|17|cm|in|abbr=}} across, while females can grow to {{Convert|11|cm|in|abbr=}}<ref name=":1">{{Cite web|url=https://caseagrant.ucsd.edu/seafood-profiles/sheep-crab|title=Sheep Crab {{!}} California Sea Grant|website=caseagrant.ucsd.edu|access-date=2019-12-28}}</ref>. The carapace is tear-shaped with a wide, rounded posterior which tapers to a point at its snout, or [[Rostrum (anatomy)|rostrum]]. There are two down-curved horns on the rostrum<ref name=":2" />. |
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While the exoskeleton, or shell, is reddish, this is often masked. Young crabs deliberately attach algae, bryozoans, sponges, and other creatures to their exoskeletons as a form of camouflage to hide from predators<ref>{{Cite journal|last=Wicksten|first=Mary K.|date=1979|title=Decorating Behavior in ''Loxorhyncus crispatus'' Stimpson and ''Loxorhychus grandis'' Stimpson|url=https://books.google.com/books?id=pbOhjfMzN2MC&pg=PA37&lpg=PA37&dq=Loxorhynchus+grandis&source=bl&ots=ajY1SMyPzg&sig=ACfU3U1c-csVz-3rO5Polm1B0-kFSxRrXA&hl=en&sa=X&ved=2ahUKEwj7wujZwtnmAhU3HTQIHSF1DpQ4KBDoATAIegQIChAB#v=onepage&q=Loxorhynchus%20grandis&f=false|journal=Crustaceana|publisher=E.J. Brill|volume=Suplement 5|pages=37 - 46|via=}}</ref>. Animals larger than {{Convert|8|cm|in|abbr=}} cease to decorate themselves. This species stops molting when it reaches sexual maturity, however, and a layer of algae often develops on the long-lived adult exoskeleton, giving these crabs a green appearance. |
While the exoskeleton, or shell, is reddish, this is often masked. Young crabs deliberately attach algae, [[Bryozoa|bryozoans]], [[Hydrozoa|hydroids]], [[Sponge|sponges]], and other creatures to their exoskeletons as a form of camouflage to hide from predators<ref>{{Cite journal|last=Wicksten|first=Mary K.|date=1979|title=Decorating Behavior in ''Loxorhyncus crispatus'' Stimpson and ''Loxorhychus grandis'' Stimpson|url=https://books.google.com/books?id=pbOhjfMzN2MC&pg=PA37&lpg=PA37&dq=Loxorhynchus+grandis&source=bl&ots=ajY1SMyPzg&sig=ACfU3U1c-csVz-3rO5Polm1B0-kFSxRrXA&hl=en&sa=X&ved=2ahUKEwj7wujZwtnmAhU3HTQIHSF1DpQ4KBDoATAIegQIChAB#v=onepage&q=Loxorhynchus%20grandis&f=false|journal=Crustaceana|publisher=E.J. Brill|volume=Suplement 5|pages=37 - 46|via=}}</ref>. Animals larger than {{Convert|8|cm|in|abbr=}} cease to decorate themselves. This species stops molting when it reaches sexual maturity, however, and a layer of algae often develops on the long-lived adult exoskeleton, giving these crabs a green appearance. |
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== Distribution and habitat == |
== Distribution and habitat == |
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Revision as of 17:23, 29 December 2019
| Loxorhynchus grandis | |
|---|---|
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Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Malacostraca |
| Order: | Decapoda |
| Suborder: | Pleocyemata |
| Infraorder: | Brachyura |
| Family: | Epialtidae |
| Genus: | Loxorhynchus |
| Species: | L. grandis
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| Binomial name | |
| Loxorhynchus grandis Stimpson, 1857
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Loxorhynchus grandis, commonly known as the sheep crab or spider crab, is a species of crab in the family Epialtidae[1]. It is the largest crab found on the California coast[2]. The species was first described to science by William Stimpson in 1857[3]. The type specimen was collected on the coast of California, near San Francisco. Fossils from the late Miocene epoch indicate that this species is at least 11.63 to 5.333 million years old[4].
Description
The sheep crab has a carapace, four sets of walking legs, and a set of claws, or chelipeds. Males are larger than females. The carapace of a male can be up to 17 centimetres (6.7 in) across, while females can grow to 11 centimetres (4.3 in)[5]. The carapace is tear-shaped with a wide, rounded posterior which tapers to a point at its snout, or rostrum. There are two down-curved horns on the rostrum[6].
While the exoskeleton, or shell, is reddish, this is often masked. Young crabs deliberately attach algae, bryozoans, hydroids, sponges, and other creatures to their exoskeletons as a form of camouflage to hide from predators[7]. Animals larger than 8 centimetres (3.1 in) cease to decorate themselves. This species stops molting when it reaches sexual maturity, however, and a layer of algae often develops on the long-lived adult exoskeleton, giving these crabs a green appearance.
Distribution and habitat
This crab lives in coastal waters from Cordell Bank, California to Punta San Bartolome, Baja California[2]. It is found in waters between 6 metres (20 ft) and 152 metres (499 ft)[6] deep. Sheep crabs are quite mobile. and forage on rocky and soft bottoms, as well as pilings[8]. This species is migratory, spending the warm months of the year in shallow waters and the cooler months in deeper waters.
Diet
The sheep crab is a scavenger-generalist in diet, eating algae, mussels, sea stars[9], small crabs, including juvenile sheep crabs and northern kelp crabs[9], and carrion.
Predators
Sheep crabs are preyed upon by sea otters[9], cabezon, California sheephead, octopus, sharks, rays, and larger sheep crabs[5].
Fishery
In the late 1970s a commercial fishery for sheep crabs developed in California. Two markets emerged, one for the large claws of the male crabs, and another for whole crabs. The fishery peaked in 1988 when 96,000 pounds of claws and 108,000 pounds of whole crabs were landed. In 1990, a California ballot initiative[10] banned the use of gill nets and trammel nets that were used to catch sheep crabs, and the fishery shrank significantly[11]. In 2018, California reported commercial landings of 503 pounds of claws and 74,863 pounds of whole crabs[12].
References
- ^ Peter Davie (2010). "Loxorhynchus grandis Stimpson, 1857". WoRMS. World Register of Marine Species. Retrieved May 24, 2012.
- ^ a b Hobday, Alistair J.; Rumsey, Scott M. (1999-07-22). "Population dynamics of the sheep crab Loxorhynchus grandis (Majidae) Stimpson 1857 at La Jolla California".
{{cite journal}}: Cite journal requires|journal=(help) - ^ Stimpson, William (1857). Crustacea and Echinodermata of the Pacific shores of North America. Smithsonian Libraries. [Boston, Boston Society of Natural History]. pp. 12–13.
- ^ Rathbun, Mary J. (1908). "Descriptions of Fossil Crabs From California". Proceedings of the United States National Museum. 35: 342.
- ^ a b "Sheep Crab | California Sea Grant". caseagrant.ucsd.edu. Retrieved 2019-12-28.
- ^ a b "Sheep crab, Reefs & Pilings, Invertebrates, Loxorhynchus grandis at the Monterey Bay Aquarium". www.montereybayaquarium.org. Retrieved 2019-12-26.
- ^ Wicksten, Mary K. (1979). "Decorating Behavior in Loxorhyncus crispatus Stimpson and Loxorhychus grandis Stimpson". Crustaceana. Suplement 5. E.J. Brill: 37–46.
- ^ "Loxorhynchus grandis, sheep crab". sealifebase.org. Retrieved 2019-12-26.
- ^ a b c "Sheep crab - Encyclopedia of Life". eol.org. Retrieved 2019-12-29.
- ^ "California State Constitution: Article X B Marine Resources Protection Act of 1990".
{{cite web}}: CS1 maint: url-status (link) - ^ Culver, Carolynn S.; Kuris, Amanda M. (May 2002). "Annual Status of the Fisheries Report". California Department of Fish and Game. p. 7-1 to 7-5.
{{cite web}}: CS1 maint: url-status (link) - ^ "Origin and Poundage of Commercial Fish Landings into California 2018". July 19, 2019.
{{cite web}}: CS1 maint: url-status (link)
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